1. Field of the Invention
The invention is directed to the provision of an inboard lock means for a power boat inboard-outboard propulsion unit to discourage theft of the stern drive portion of the propulsion unit.
2. Description of Related Art
In power boats the inboard-outboard propulsion unit is a powerplant which couples a typical inboard engine to a drive unit which is essentially the lower unit of an outboard motor and is mounted outboard at the stern of the boat. The drive unit is known by various names--outdrive, outboard drive, stern drive, transom drive and "Z" drive. A horizontal drive shaft projects aft from the engine through the transom, above the water line, and is geared to a vertical shaft of the stern drive. The latter, mounted outside and rearward of the transom, functions essentially like a conventional outboard motor, swinging from side to side for steering and tilting upward for beaching or upon striking an underwater obstacle. The inboard-outboard propulsion unit thus combines the advantage of a permanently installed relatively powerful inboard engine with the handling and steering capability characteristic of the outboard motor.
The inboard-outboard propulsion unit has become quite popular and is presently installed on boats from about 15 feet in length up to about 30 feet in length. With this increasing popularity, the incidence of thefts of stern drives has risen. The stern drive is secured to the transom of a boat through a gimbal housing which is integral with the stern drive. It is relatively easy to loosen and remove the bolts attaching the gimbal housing to the stern drive, thus freeing the stern drive and enabling one to withdraw the drive shaft (which has splined shaft connection with the engine) from the engine through the passage provided in the transom for the drive shaft. The stern drive with the drive shaft are thus separated from the boat.
Bolt locks are available on the market as a measure to prevent or delay these thefts and by replacing one of the standard bolts with a bolt lock at least some delay of the projected theft is doubtless effected. However, since the lock is readily visible from the exterior of the boat, a perpetrator would be able to readily identify the lock without boarding the boat, evaluate its weakness and plan a strategy to defeat it. Once the boat lock is defeated, the remaining bolts may be removed and the theft accomplished in a relatively short time, all without ever boarding the boat. There have been recent instances in which stern drives secured by such boat locks were stolen.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an inboard lock for the stern drive of a power boat which will compel one intent on theft of a stern drive to first gain entry to the engine compartment and labor there to defeat the lock.
It is another object of the present invention to provide a locking collar for a stern drive wherein the locking collar is not visible from outside the boat.
It is yet another object of the present invention to provide a locking collar which is easily installed to hinder theft of stern drives.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.